Gotze admits he remains in regular contact with the former BVB coach.
And he recalled to the Players' Tribune: "He knew how to handle me. He was an outstanding coach, but his personality was the most important thing for me as a young player.
"I have never met a manager in football who was so naturally funny . I will never forget the time I ran into him in Dusseldorf during the summer. He was going to see the specialist there to have his hair transplant done.
"This became big news in Germany, but he was so funny about it. He was smiling, telling me all about it — how cool it was going to look and everything.
"And then as he was leaving, he just gave me a wink and he said, 'Mario, don't worry, I will save the phone number.'
"I said, 'What do you mean?'
"He said, 'The doctor's number. I'll save it for you. In a few years, you might need it.'"
Gotze also said: "When I was 17 or 18, and not giving 100% in training, he would be so intimidating. He used to come running over and get right up in my face and start shouting at me.
"I can't really translate from German perfectly, but you know how he talks, with his teeth grinding: 'You have to have more passion! You have to give everything! F***! Come on!!!'
"Then after training, he would be completely calm again, and he'd take you aside and say, 'Mario, how are you? Let's talk about life. What's happening?'"